Differential amplifiers are used in a variety of circuit applications. For example, one application in which differential amplifiers are used is to produce a reference signal. In the idealized case, a differential amplifier that receives equivalent voltages at the positive input and the negative input generates a zero voltage at the output. Non-idealized, e.g., “real-world,” differential amplifiers, however, suffer from an imperfection referred to as “input offset voltage.” Real world differential amplifiers generate a voltage at the output despite receiving equivalent voltages at the positive and negative inputs due, for example, to various mismatches and/or imperfections in the constituent devices of the differential amplifier. The amount by which one input signal must be altered with respect to the other input signal to shift the output of the differential amplifier to zero volts is referred to as the input offset voltage.
The non-idealized behavior of a differential amplifier described above can be problematic in situations where a high degree of accuracy is desired. For example, in circuit applications where the output of the differential amplifier is used as a reference, unless the input offset voltage is accommodated in some fashion, the output of the amplifier will not be an accurate representation of the input. This inaccuracy in reproducing the input signal can introduce errors into any process relying on the amplifier for an accurate reference signal.